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The motor starts in star but does not run in delta?
Whenever you start a big heavy electric motor, you need to start it slowly to prevent the rotor overheating and drawing an enormous current or to prevent damage to the load it is driving. When the windings of a 3-phase motor are connected in STAR the current is reduced by a factor of (one over root three) times (the normal running current that is taken when it is connected in DELTA.)Once the motor picks up speed, the connection is changed to DELTA so that the motor runs at full speed and torque from then on. It's a bit like using the gears of an automobile.For more information, see the answers to the Related Questions shown below.
What device may be wired into the starting circuit of a motor to improve the starting torque?
I assume a 3 phase, AC induction motor. A star delta starter or a soft starter can be used. A soft starter is better compared to a star delta starter, but it is more expensive.
Why star delta starter is more efficient?
The star-delta starter allows the motor to start with one third its normal power, minimizing inrush current and heating, thus extending the life of the motor and its control center. When a motor is connected in star the total output torque is only a third of the total torque that could be produced running in delta. Please see related questions and links.
Why using on motor star delta starter?
because at the starting the induction motor drawn a heavy current thats why we use starter to increase the starting resistance of the induction motor!
IWant to see the connection of the daigram Star and Delta connections?
Google star delta motor connections. If a motor is wired in star-delta (Yd), it starts up with lots of torque and then switches over to delta for normal "running". This is because the start-up current per phase when delta connected is much larger than star.
What is the advantage of a Star Delta Motor Starter?
The inrush current to the starting motor is lower due to the the motor coils being in series across the line creating a higher impeadence. When the starter connects to delta connection the motor is already turning and it does not have to go through the locked rotor phase. This system is being phased out now with the use of electronic soft starts and by-pass contactors.To start a motor direct on line (DOL) in delta requires approximately 6 to 8 times the full load current of the motor and delivers full torque. Delta places 415v across each of the windings on the motor. A Star-Delta starter starts the motor in Star which places 240v across each winding on the motor. This results in a lower starting current and also a lower starting torque.
Why rotor contactor in external resistance of slipring motor connected in delta?
rotor contactor are used to cut the resistance in slip-ring motor connected through resistance box. resistance is proportional to torque. so by controlling rotor contactor resistance can be controlled and hence torque can be controlled. for more information check torque and speed characteristic of wound motor.
Is DOL starter is sufficient for 10HP 2880 RPM motor?
If the application is high starting torque, then go for star delta or soft starters. If not DOL will do.
How do you calculate hydraulic motor torque?
how to calculate hydraulic motor torque
What is a timer in a star delta starter?
A timer in star delta starter for a three phase motor is an electronic device designed to do the change over or transition from star connection - using which the motor suns on a reduced voltage and current and produces less torque - to the delta connection necessary for running the motor at its full power, using high voltage and current to produce a high torque. The timing interval that is set is dependent how long the motor needs to start up from standstill to normal speed. Some motors require 15 seconds for the initial startup in star connection and after that given value of time the timer signals to the star contactor to go to the open position and the main delta contactor to go to the closed position, thus forming the delta circuit.
Can you draw star delta diagram in PLC logic?
PLC logic is a digital computer used to automate electromechanical processes. The Star delta diagram is a diagram for a simple circuit that has the capabilities of starting a high horse power motor. A star delta diagram can be drawn in PLC Logic.
Why connection of crane motor is delta star?
Starting in star reduces massive in-rush current while supplying great torque to overcome inertia. Once running the most efficient mode of operation for acceleration and constant drive is delta.
